1. Field of the Invention
The present invention relates to a corrugating machine, and more particularly to a corrugating machine provided with adjustable adhesion means.
2. Description of the Prior Art
At first, one example of a corrugating machine in the prior art will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, paste (starch) d is applied to corrugated crest portions of a single-faced corrugated cardboard sheet a, b consisting of a liner c and a corrugated core paper sheet b which is manufactured by a single-facer in a preceding stage, by means of a paste feeder 13 in a glue machine 2 as shown in FIG. 5, and a liner c is preheated. The single-faced cardboard sheet a, b and the liner c are joined at an introducing port section of a double-facer 3, and in a heating part 3a forming a preceding stage of the double-facer 3 they are pinched between a plurality of heating boxes 20 and a canvas belt 19 adapted to be driven and also conveyed as pressed by a group of weight rollers 21. During passage through the heating part 3a, due to heating by the heating boxes 20 containing high-temperature steam therein, the paste d is solidified, hence the liner c is stuck to the single-faced corrugated cardboard sheet a, b and a double-faced cardboard sheet a, b, c is formed. This is cooled in a cooling part 3b in the succeeding stage and ejected from the side of a roller 18.
The paste d applied to the corrugated crest portions of the core paper sheet b and, in an ideal case, a predetermined amount d' of paste penetrates into the core paper sheet b as shown in FIG. 3, whereas in the case where an amount d" of penetrated paste is too little as shown in FIG. 4(A), or in the case where an amount d" of penetrated paste is too much as shown in FIG. 4(B), a strong adhesion force cannot be obtained.
In the above-described corrugating machine in the prior art, the distance between the glue machine 2 and the heating part 3a of the double facer 3 is constant and cannot be changed. In addition, depending upon whether the traveling speed of the single-faced corrugated cardboard sheet a, b is fast or slow, and depending upon the material and thickness of the core paper sheet and the permeability of the paste d caused by the state of the paste, the amount of penetration of paste into the core paper sheet can become excessive or insufficient, hence the degree of adhesion can vary widely, resulting in uneven distribution of strength of the double-faced corrugated cardboard sheet, and thereby the quality of the products can be greatly degraded. Furthermore, if the amount of penetration of paste becomes too much, it can cause the corrugated crest portions to be crushed.
As described above, in the corrugating machine in the prior art, since the glue machine for applying paste to the corrugated crest portions of the core paper sheet in a single-faced corrugated cardboard sheet and the heating part of the double facer for forming a double-faced corrugated cardboard sheet are fixedly installed with the distance between the glue machine and an introducing port of the heating part held constant, the amount of penetration of paste applied to the corrugated crest portions of the core paper sheet vary greatly depending upon various conditions such as the sheet traveling speed, the material and thickness of the core paper sheet, and the state of the paste, hence adhesion in the double facer becomes uneven, and thus degradation of quality was inevitable.